An OLED (Organic Light-Emitting Diode) display is used more and more widely in all kinds of portable electronic devices because of its lightweight, power saving and other characteristics.
An OLED refers to a diode emitting light through current carrier injection and recombination by use of an organic light-emitting material driven by an electric field. A transparent electrode and a metal electrode are used as one of an anode and a cathode of a device respectively, and under the driving of a certain voltage, electrons and holes are injected into electron and hole transport layers through an electron injection layer and a hole injection layer respectively from the cathode and the anode, then are migrated to a light emitting layer through the electron and hole transport layers respectively, and meet each other in the light emitting layer to form excitons and excite photons which emit visible light through radiative relaxation.
Because of transmission and reflection characteristics of an anode layer and a cathode layer, the light emitted by the organic light-emitting layer is reflected back and forth between the anode layer and the cathode layer to form a microcavity effect. The microcavity effect can enhance a resonant wavelength and improve the color purity and light-emitting efficiency of an OLED device.
However, due to different intrinsic emission wavelengths of different color lights, the microcavity lengths required by different color lights are different. When manufacturing an organic light-emitting display panel (hereinafter referred to as an OLED display panel), it is usually necessary to adjust the cavity length of a microcavity according to the color of the light emitted by each pixel. For example, when manufacturing an R (red) G (green) B (blue) three-color OLED display panel, three fine masks for three colors, i.e., R, G and B, respectively, are needed to form optical compensation layers of R, G, and B pixels on a hole transport layer. Then, three fine masks for the three colors, R, G and B, respectively, are used to form organic light emitting layers on the corresponding optical compensation layers. Thus, the number of the fine masks required for manufacturing the OLED display panel is larger, resulting in that the process for manufacturing the OLED display panel is complex and the yield is reduced.